140 volts could be dangerous if working on radios designed for 110 or 112 volts.

- Leigh

So don't turn it up to 11.

I use it with a dimbulb setup to account for the drop in voltage. That way i can still have near 110V but still keep the protection.

The Hallicrafters I'm working on will not work with the 60W bulb on the dim-bulb setup. It drops to about 75V. I could go out and buy a 100W bulb but easier to just crank it up a to 90V with the variac on 130..

The Hallicrafters I'm working on will not work with the 60W bulb on the dim-bulb setup. It drops to about 75V. I could go out and buy a 100W bulb but easier to just crank it up a to 90V with the variac on 130..

No radio is intended to work properly on a DBT.

DBTs are not designed to power a working radio. They're designed to find short circuits and similar wiring faults.

Once they pass that test, replace the bulb with a screw-in fuse and run the set at proper voltage. You should never run any set on reduced line voltage. Doing so will tell you nothing, and could damage the set.

Is that a dial ring that I see touching your thumb? If so, does it have a voltage scale on it with a pointer on the knob? If the scale goes up over line voltage, you may want to hook it up with the boost connection to make the dial somewhat track. Or, if it only goes to the line voltage, then the non boost connections.

To amplify on J. Hill's comment, many of those dial rings were printed on both sides. One side was calibrated for 0 to 100% line voltage and the other for 0 to 117% (or 130 volts). You mounted the dial scale so that the correct calibration for the intended use was showing.

140 volts could be dangerous if working on radios designed for 110 or 112 volts.

- Leigh

If I am building a variac or powerstat project that may have a use for the higher output voltage, I will include a DPST switch to apply the AC input to either the terminal that produces line in = max volts out, or to the terminal that produces ~140 volts out. The second pole of the DPST switch powers a prominent looking pilot light when the higher voltage position is selected.

Member "comm-nav" wrote above (w/ pictures) about mod's to make a SuperiorPowerstat-brand (or most GenRadVariac) variac ranges switchable. Am writing to inform that this feature is already standard with many models of the STACO branded variacs, and some of the FisherBrand (beige/tan case painted, before Thermo-Fisher) 1960's-80's models spec'd by Fisher, built by Superior company. So if you buy the STACO or older FisherBrand, then you don't have to make this mod, it's already there. Fred